Expansible intravertebral implant system with posterier pedicle fixation

ABSTRACT

The present invention relates to an expansible intravertebral implant system comprising an intravertebral implant ( 1 ) with an expandable anterior part ( 11 ), which is expansible in a vertebral body, and a posterior part; and a pedicle fixation ( 2 ) having at least one hollow portion for receiving the posterior part. The present invention also relates to said expansible intravertebral implant system additionally comprising a posterior element ( 3 ), arranged partially outside the vertebra and rigidly connected to the pedicle fixation ( 2 ), for serving as an anchoring point for at least one intravertebral rod or at least one system of artificial ligaments.

FIELD OF THE INVENTION

The present invention relates to an expandable intravertebral implant system with posterior pedicle fixation. More particularly, the present invention relates to an expandable intravertebral implant system offering enhanced vertebral anchoring by adding a pedicle dowel firmly anchored in a vertebral pedicle.

STATE OF THE RELATED ART

Several vertebroplasty techniques are known for performing vertebral correction enabling a vertebra deformed following bone compression, for example due to osteoporosis or an injury, to return to the initial shape or morphology thereof.

For example, the kyphoplasty technique is known, consisting of introducing an inflatable balloon into a vertebra, then sending a pressurised fluid into the balloon placed in the vertebra in order to force the cortical envelope of the vertebra, and particularly the lower and upper vertebral plates to return to a corrected shape under the effect of the pressure. Once the cortical bone envelope has been corrected, the balloon is then deflated, and removed from the vertebra, in order to be able to inject therein a bone cement intended to give the corrected vertebra a stable mechanical strength over time.

Through the international patent application WO2005/120400 in particular, an expandable implant is known, comprising a first and a second opposite plates, suitable for respectively forming a first and a second bearing surfaces in a vertebral body; these two bearing surfaces being called upon to separate from one another along a predefined expansion plane. The expandable implant is positioned in the vertebral body, and the plates are deployed along an expansion plane which corresponds to the bone correction plane sought. A bone cement is then injected in order to stabilise the bone correction.

The bone cement may be injected with a relatively low pressure by means of the implant which remains in position in the vertebral body.

In the case of the most severe injuries, the use of the methods cited above may prove to be insufficient. The repair of vertebral fractures, and particularly vertebral fractures induced by compression is then preferentially performed by means of screws inserted into the pedicles of the over- and underlying vertebrae of the compressed vertebra, these screws being associated with posterior rods, thus mechanically connecting the two over- and underlying vertebrae to enable vertebral consolidation. Pedicle screws are well-known in the prior art. Screws such as those described in the U.S. Pat. No. 5,209,753 are particularly known.

The drawback of this technique lies in the fusion of two vertebral joint levels caused by the fixation of the posterior rods connecting the over- and underlying vertebrae. Furthermore, these methods do not always enable bone correction of the compressed vertebra but merely the stabilisation of three adjacent vertebrae and thus the locking of two joint levels. The surgical act associated with this procedure is furthermore very invasive and requires access to at least two vertebrae.

In order to remedy these drawbacks, it appears to be necessary to provide a device enabling the repair of vertebral fractures, and particularly severe vertebral fractures caused by compression, preventing fusion and enabling consolidation, at the pedicle, of an expandable intravertebral implant situated in the vertebral body.

As such, the aim of the invention is to associate with an expandable intravertebral implant, positioned in a vertebral body, a pedicle fixation (for example dowel or sleeve), intended to be anchored in the pedicle. This pedicle fixation ensures high-quality support and anchoring of the bone. Indeed, while the vertebral body consists of spongy bone, having a high porosity of 30 to 90%, the pedicle consists of cortical bone, having a porosity of 5 to 30%, thus offering strong mechanical support for the intravertebral implant and making it possible to reconstruct vertebral fractures, and particularly vertebral fractures caused by compression, even the most severe.

Extendable bone implant systems comprising an additional anchoring in the pedicle bone are known, such as for example the systems described in the patent applications EP 2 074 956 and US 2009/005821. However, these systems describe an expandable member rigidly connected to said pedicle fixation, for example by screwing both parts. For this reason, the direction of expansion of the expandable member and the positioning of the member in the vertebral body are directly dependent on the position of the pedicle fixation.

The invention has the advantage of enabling the deployment of the expandable intravertebral implant independently, along at least one degree of freedom, of the position of the pedicle fixation. The implant system also makes it possible to secure (i.e. lock all the degrees of freedom) said extendable intravertebral implant with respect to the pedicle fixation, when the implant system is positioned in extension in the vertebra.

Advantageously, a posterior element acting as a connection system is associated with the pedicle fixation element, making it possible to adjoin to the expandable intravertebral implant means completing the bone correction, for example using posterior rods or other system intended to stabilise the fracture site further.

As such, the present invention ensures vertebral correction using a modular expandable intravertebral implant system with posterior pedicle fixation.

SUMMARY

The invention thus relates to an expandable intravertebral implant system comprising an intravertebral implant comprising an expandable anterior part in a vertebral body and a posterior part; and a pedicle fixation having at least one hollow portion for receiving the posterior part of the intravertebral implant.

According to one embodiment, the pedicle fixation comprises an external thread ensuring the anchoring of said pedicle fixation in a vertebral pedicle.

According to one embodiment, the pedicle fixation comprises a hollow posterior inner portion and a hollow anterior inner portion wherein the posterior part of the intravertebral implant can move along at least one degree of freedom.

According to one embodiment, the pedicle fixation comprises a main axis and the posterior part of the intravertebral implant can move in translation and in rotation, along the main axis of the pedicle fixation, in the anterior inner portion of the pedicle fixation; in such a way that the direction of expansion of the anterior part of the anterior part of the intravertebral implant is independent from the position of the pedicle fixation in the vertebral pedicle.

According to one embodiment, the anterior part of the intravertebral implant comprises a first and a second plates, suitable for respectively forming a first and a second bearing surfaces in a vertebral body; these two surfaces being suitable for being separated from one another along a predefined expansion plane.

According to one embodiment, the anterior inner portion comprises at least one groove on the inner surface thereof.

According to one embodiment, a posterior portion of the posterior part of the intravertebral implant comprises a cylindrical recess and at least one securing means suitable for locking in rotation and in translation the relative movements between the intravertebral implant and the pedicle fixation.

According to one embodiment, the securing means comprises at least one through hole, passing through the posterior portion and a peripheral chamber to the surface of the posterior portion in fluid communication with the at least one through hole.

According to one embodiment, the securing means comprises at least two slots extending axially along the posterior portion, an internal thread and a flared posterior end; suitable for engaging with a conical expansion cap.

According to one embodiment, the posterior element is secured to the pedicle fixation by means of a threaded rod screwed into an internal thread of the posterior inner portion.

According to one embodiment, the posterior element comprises a posterior portion suitable for assembly with additional posterior fixation elements such as rods or artificial ligaments.

BRIEF DESCRIPTION OF THE FIGURES

Further specific features and advantages will emerge clearly from the description hereinafter, by way of indication and in no way limiting, with reference to the appended drawings, wherein:

FIG. 1 is an exploded view of the implant system according to one embodiment of the present invention.

FIG. 2 is a side view of the intravertebral implant according to one embodiment of the present invention.

FIG. 3A is a side view of the pedicle fixation according to one embodiment of the present invention.

FIG. 3B is a sectional view of the pedicle fixation according to one embodiment of the present invention.

FIG. 4 is a perspective view of the posterior element according to one embodiment of the present invention.

FIG. 5 is a side view of the implant system according to one embodiment of the present invention, mounted on an instrument suitable for the insertion of the implant system.

FIG. 6A is a side view of the implant system, according to one embodiment of the present invention, placed in a vertebra; said vertebra being represented as transparent, visible merely by the outlines thereof.

FIG. 6B is a top view of the implant system, according to one embodiment of the present invention, placed in a vertebra; said vertebra being represented as transparent, visible merely by the outlines thereof.

FIG. 7A is a sectional view of the implant system according to one embodiment of the present invention, prior to expansion of the anterior part of the implant.

FIG. 7B is a sectional view of the implant system according to one embodiment of the present invention, after expansion of the anterior part of the implant.

FIG. 8A is a sectional view of the implant system, after expansion of the anterior part of the implant illustrating the means for securing the pedicle fixation to the intravertebral implant according to one embodiment of the present invention.

FIG. 8B is a perspective view of the intravertebral implant, after expansion of the anterior part of the implant illustrating the means for securing the pedicle fixation to the implant according to one embodiment of the present invention.

FIG. 8C is a perspective view of the pedicle fixation particularly illustrating the anterior inner portion according to one embodiment of the present invention.

FIG. 9A is a sectional view of the implant system, after expansion of the anterior part of the implant illustrating the means for securing the pedicle fixation to the intravertebral implant according to one embodiment of the present invention.

FIG. 9B is a perspective view of the implant system, after expansion of the anterior part of the implant illustrating the means for securing the pedicle fixation to the intravertebral implant according to one embodiment of the present invention.

FIG. 10A is a side view of the implant system according to one embodiment of the present invention placed in a vertebra; said vertebra being represented as transparent, visible merely by the outlines thereof.

FIG. 10B is a sectional view of the implant system according to one embodiment of the present invention placed in a vertebra; said vertebra being represented as transparent, visible merely by the outlines thereof.

The drawings in the figures are not to scale. Obviously, the scope of the invention is not restricted to examples of embodiments more specifically described and represented with reference to the appended figures; on the contrary, it includes any alternative embodiments.

REFERENCES

-   1 Anterior part of the intravertebral implant, -   11 Posterior part of the intravertebral implant, -   121 Shoulder, -   122 Cylindrical recess, -   123 Chamber, -   124 Through hole, -   125 Slot, -   126 Internal thread, -   127 Flared posterior end, -   128 Posterior portion of the posterior part of the intravertebral     implant, -   13 Central traction tube, -   131 Through hole, -   2 Pedicle fixation, particularly pedicle dowel, -   21 External thread, -   22 Posterior inner portion, -   221 Internal thread, -   23 Anterior inner portion, -   231 Groove, -   24 Means for rotating the pedicle fixation—Notch, -   25 Entry chamfer, -   3 Posterior element, -   31 Anterior portion, -   311 External thread, -   32 Posterior portion, -   33 Bearing surface, -   4 Vertebra, -   5 Insertion instrument, -   51 Cannula rotatably connected to the pedicle fixation, -   52 Expansion tube, -   6 Conical expansion cap.

DETAILED DESCRIPTION

The present invention relates to an expandable intravertebral implant system with posterior pedicle fixation.

According to a first embodiment, the implant system comprises an intravertebral implant associated with a pedicle fixation ensuring additional anchoring at the vertebral pedicle.

According to a second embodiment, as represent in FIG. 1, the implant system comprises an intravertebral implant 1 associated with a pedicle fixation 2 and with a posterior element 3 suitable for connecting, posterior to the vertebra, any device intended to stabilise, reinforce or repair the vertebral fracture, particularly the vertebral fracture caused by compression.

Intravertebral Implant

As represented in FIG. 2, the intravertebral implant 1 according to the present invention comprises an anterior part 11 and a posterior part 12.

According to one embodiment, the anterior part 11 corresponds to a deformable and expandable intravertebral implant 1 such as the SpineJack® implant marketed by the company VEXIM, known to those skilled in the art and also described in the patent application EP 1 778 136, incorporated herein by reference. It is specified that those skilled in the art, on reading said patent application, would readily find the features required for the embodiment of the present invention. In particular, the anterior part 11 of the intravertebral implant 1 of the present invention consists of an expandable part enabling bone correction and comprising:

-   -   a predetermined single expansion plane, intrinsic to said         anterior part 11,     -   a first and a second opposite plates, suitable for respectively         forming a first and a second bearing surfaces in a vertebral         body; these two bearing surfaces being intended to separate from         one another along said expansion plane upon expansion of the         implant,     -   a first and a second supports for each of said first and second         plates, situated respectively thereunder, and     -   means for setting a predetermined expansion value, including a         veil of material arranged between said support and a         corresponding plate, said veil having a predetermined thickness         making it possible to monitor the expansion of the implant.         According to one embodiment, said anterior part 11 also         comprises a central traction tube 13 suitable for controlling         the expansion of the first and second plates. According to one         alternative embodiment, the anterior part 11 of the         intravertebral implant 1 corresponds to any intravertebral         implant known to those skilled in the art which is deformable,         expandable and suitable for remaining in the vertebral body         after expansion.

According to one embodiment, as represented in FIGS. 7A-B, 8A-B, 9A-B and 10A-B, the central traction tube 13 is hollow and comprises at least one through hole 131 suitable for injecting a filling material into the vertebra 4, such as bone cement, after the expansion of the first and second plates. According to one embodiment, the central traction tube 13 comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 through holes 131. According to one embodiment, the through hole(s) 131 pass(es) radially through the central traction tube 13 so as to enable fluid communication between the inner conduit and the outer surface. According to one embodiment, the central traction tube 13 comprises a plurality of through holes 131 regularly distributed on the surface thereof. According to one embodiment, the at least one through hole 131 is situated between the two plates so as to be in fluid communication with the inside of the vertebra after the expansion of the implant and the separation of the two plates. Advantageously, the injection of a filling material into the vertebra 4 makes it possible to hold the anterior part 11 of the implant 1 in position in the vertebral body after expansion. According to one embodiment, the filling material is a biocompatible bone cement, for example an ionic cement, a phosphocalcium cement, an acrylic cement or a composite thereof, or a resin. According to one embodiment, the filling material solidifies after injection. Advantageously, the solidification of the filling material makes it possible to consolidate the vertebra 4 and reinforce the strength of the implantation of the implant system in the vertebra 4.

According to one embodiment, the posterior part 12 is a hollow cylindrical body connected, at the anterior end thereof, to the posterior end of the anterior part 11 by a shoulder 121. Said posterior part 12 comprises a cylindrical recess 122 through which a central traction tube 13, initially situated in the anterior part 11, can slide. By pulling on the central traction tube 13, the central traction tube 13 slides in the cylindrical recess 122 of the posterior part 12 and the anterior and posterior ends of the anterior part 11 move closer, causing the expansion of the first and second plates of the anterior part 11 of the intravertebral implant 1. The central traction tube 13 is suitable for controlling the deployment of the expandable deformable anterior part 11. Once the traction tube 13 has been pulled inside the recess 122, the tube can no longer return to the initial position thereof, which holds the expansion of the anterior part 11, pending the injection of bone cement or substitute.

According to one embodiment illustrated in particular by FIG. 8B, the posterior part 12 of the intravertebral implant 1 comprises a cylindrical recess 122 and at least one through hole 124. Advantageously, the at least one through hole is situated in the posterior portion 128 of the posterior part 12. According to one embodiment, the posterior portion 128 corresponds to the portion of the posterior part of the intravertebral implant 12 which remains permanently inside the anterior inner portion 23. According to one embodiment, the cylindrical recess 122 passes through the entire posterior part of the implant 12. According to one embodiment, the posterior part of the intravertebral implant 12, and particularly the posterior portion 128 further comprises a portion with a reduced outer diameter thus defining a peripheral chamber 123. According to one embodiment, the at least one through hole 124 passes through the posterior part of the implant 12 from the cylindrical recess 122 to the peripheral chamber 123. According to one embodiment, the posterior part 12 of the implant, and particularly the posterior portion 128 thereof comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 through holes 124. According to one embodiment, the through holes 124 are regularly distributed on the posterior portion 128.

According to one embodiment illustrated by FIG. 9B, the posterior part of the intravertebral implant 12 comprises a cylindrical recess 122 and at least one slot 125 through the posterior part 12 and extending axially. Advantageously, the at least one slot 125 is situated in the posterior portion 128 of the posterior part 12. According to one embodiment, the posterior portion 128 corresponds to the portion of the posterior part of the intravertebral implant 12 which remains permanently inside the anterior inner portion 23. According to one embodiment, the cylindrical recess 122 passes through the entire posterior part of the implant 12. According to one embodiment, the posterior part of the intravertebral implant 12, and particularly the posterior portion 128 further comprises an internal thread 126 situated on the inner surface of the cylindrical recess 122. According to one embodiment, the posterior part of the intravertebral implant 12, and particularly the posterior portion 128 further comprises a flared posterior end 127 suitable for engaging with a conical expansion cap 6. According to one embodiment, the posterior part 12 comprises at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 slots 125. According to one embodiment, the slot 125 extends along all or part of the posterior portion 128. According to one embodiment, the thread 126 extends along all or part of the posterior portion 128.

According to one embodiment, the expansion of the intervertebral implant 1 is not due to the injection of a product into the posterior part of the implant 1. However, the injection of a filling material can make it possible to stabilise the implant once in the expansion position thereof. According to one embodiment, the intervertebral implant 1 does not comprise a pouch intended to be filled with a product (e.g. a filling material) so as to enable the expansion of the pouch. According to one embodiment, the injection of a filling material through the anterior part 11 alone, does not allow the expansion of the intravertebral implant 1.

According to one embodiment, the posterior part 12 of the intravertebral implant 1 does not comprise an outer thread intended to be screwed with the pedicle fixation 2.

Pedicle Fixation

As represented in FIG. 3A, the pedicle fixation 2 according to the present invention comprises at least one thread 21. According to one embodiment, the pedicle fixation 2 comprises a thread 21 on the outer surface of the pedicle fixation 2. Said external thread 21 is suitable for providing bone anchoring in the pedicle. The anchoring of the pedicle fixation 2 in a vertebral pedicle offers additional mechanical support to the intravertebral implant 1, and particularly to the expandable anterior part 11 of said implant 1. The insertion of the pedicle fixation 2 in the bone tissue is facilitated by a chamfer 25 situated at the anterior end of the pedicle fixation 2. According to one embodiment, the outer surface of the pedicle fixation 2 has no texture other than that induced by an external thread, such as for example a meshed, striated or mottled structure. As represented in FIG. 3B, the pedicle fixation 2 is a hollow cylindrical pedicle dowel or sleeve comprising a posterior inner portion 22 and an anterior inner portion 23. According to one embodiment, the pedicle fixation 2 is not a solid pedicle screw comprising a hollow inner partial portion. According to one embodiment, the pedicle fixation 2 is hollow along the entire length thereof. According to one embodiment, the posterior 22 and anterior 23 inner portions do not have the same surface condition.

According to one embodiment, the posterior inner portion 22 comprises an internal thread 221 or any other means within the scope of those skilled in the art for connecting the fixation 2 to a posterior element 3.

According to one embodiment, the anterior inner portion 23 comprises a bore defining a hollow portion for receiving the posterior part 12 of the intravertebral implant 1. According to one embodiment, the surface of the anterior inner portion 23 is smooth. According to one embodiment, the surface of the anterior inner portion 23 is not threaded. According to one embodiment, the intravertebral implant 1, and particularly the posterior part 12, does not pass through the entire hollow pedicle fixation 2. According to one embodiment, the posterior part 12 of the intravertebral implant 1 is intended to be inserted inside the anterior inner portion 23. According to one embodiment, the posterior part 12 acts as a guide for the pedicle fixation 2. The shoulder 121 thus acts as a guiding stop for the fixation 2. According to one embodiment, the posterior part 12 of the intravertebral implant 1 can move along at least one degree of freedom, preferentially 2 degrees of freedom in the anterior inner portion 23 of the pedicle fixation 2. According to one embodiment, the posterior part 12 of the intravertebral implant 1 is sliding in the anterior inner portion 23. According to one embodiment, the mechanical link between the posterior part 12 and the anterior inner portion 23 is a sliding pivot link. According to one embodiment, the pedicle fixation 2, particularly the pedicle dowel, defines a main axis. According to this embodiment, the posterior part 12 of the intravertebral implant 1 can move in rotation and in translation along said main axis in the anterior inner portion 23 of the pedicle fixation 2.

Advantageously, the anterior portion 23 enables the expansion of the intervertebral implant 1 independently of the anchoring of the pedicle fixation 2 in the vertebral pedicle. Indeed, the degree of freedom in translation along the main axis of the pedicle fixation 2 makes it possible not to constrain the positioning (i.e. the advance due to deployment) of the intervertebral implant 1 in the vertebral body. Furthermore, the degree of freedom in rotation about the main axis of the pedicle fixation 2 makes it possible not to constrain the direction of expansion of the intervertebral implant 1. As such, the intervertebral implant 1, when deployed, adapts the deployment position thereof according to the medium wherein it is deployed (i.e. the vertebral body).

According to one embodiment, the anterior inner portion 23 does not comprise an outer thread. According to one embodiment, the anterior inner portion 23 and the intervertebral implant 1 are not screwed.

According to one embodiment, the anterior inner portion 23 further comprises at least one groove 231, as represented in FIG. 8C. According to one embodiment, the anterior inner portion 23 comprises at least one axial groove (i.e. a groove parallel with the z axis). According to one embodiment, the anterior inner portion 23 comprises at least one transverse groove (i.e. perpendicular to the z axis). According to one embodiment, the anterior inner portion 23 comprises at least one oblique groove 231.

According to one embodiment, the anterior inner portion 23 comprises at least one axial and/or transverse and/or oblique groove 231. According to one embodiment, the at least one groove 231 comprises a non-constant cross-section. According to one embodiment, the anterior inner portion 23 comprises at least 2, 3, 4, 5, 6, 7, 8, 9, 10 grooves 231. According to one embodiment, the grooves are regularly distributed on the inner surface of the anterior portion 12. According to one embodiment, the pedicle fixation 2 comprises at least one notch 24, or any other means within the scope of those skilled in the art, suitable for rotating the pedicle fixation 2, using an insertion instrument 5.

Posterior Element

As represented in FIG. 4, the posterior element 3 according to the present invention comprises an anterior portion 31 consisting of a rod, preferably a threaded rod 311 engaging with the internal thread 221 of the pedicle fixation 2, thus enabling the fixation of the posterior element 3 to the pedicle fixation 2. The posterior element 3 also comprises a posterior portion 32, external to the vertebra 4, the geometry whereof makes it possible to carry out assembly functions with complementary posterior fixation elements known to those skilled in the art such as rods or artificial ligaments. Any other assembly configuration with other systems known to those skilled in the art can be envisaged. The posterior element 3 also comprises a bearing surface 33 against bone tissue or against the posterior portion of the pedicle fixation 2, according to the choice made by the operator and/or the penetration of the pedicle fixation 2 in the pedicle bone.

Operation

After the creation of an approach and the boring of the vertebral pedicle, the implant system comprising the pedicle fixation 2 and the vertebral implant 1 wherein the posterior part 12 is inserted in the anterior inner portion 23 of the pedicle fixation 2 is inserted, and then screwed, into the pedicle using an insertion instrument 5, as represented in FIG. 5. Said insertion instrument 5 comprises a working cannula 51 rotatably secured (i.e. connected) to the pedicle fixation 2 by means of the notches 24 for screwing the pedicle fixation 2 in the pedicle. Said insertion instrument 5 also comprises an expansion tube 52 situated along the main axis of the insertion instrument 5 and it is configured to traverse at least the length of the posterior inner portion 22. The expansion tube 52 is secured (i.e. connected) to the posterior part 12 of the intravertebral implant 1, and particularly secured to the central traction tube 13 of the intravertebral implant 1. The insertion depth of the implant system is controlled by the screwing of the external thread 21 of the pedicle fixation 2 in the bone tissue, so as to position the intravertebral implant 1 optimally in the vertebral body. The positioning of the intravertebral implant 1 in axial rotation is controlled by the operator independently of the insertion of the pedicle fixation 2, using the tube 52 so as to retain an expansion plane, for example a cranio-caudal expansion plane of the intravertebral implant 1 regardless of the screwing angle obtained during the insertion of the pedicle fixation 2. As represented in FIGS. 6A, 6B, 10A and 10B, the intravertebral implant system according to the present invention is inserted through a vertebral pedicle, the intravertebral implant 1 then being situated in the vertebral body and the pedicle fixation 2 being anchored in the pedicle.

According to one embodiment, after insertion of the implant system, the pedicle fixation 2 is securely fixed in the pedicle and the intravertebral implant 1 is partially secured to the pedicle fixation 2 by the cylindrical posterior part 12 thereof. Indeed, the cylindrical posterior part 12 is inserted into the anterior inner portion 23 thus locking the rotation movements about the y and x axes and locking the translations along said x and y axes. For this reason, these locked degrees of freedom ensure partial securing between the cylindrical posterior part 12 inserted into the anterior inner portion 23. The term securing denotes the locking of all the degrees of freedom between the pedicle fixation 2 and the intravertebral implant 1. The term partial securing denotes the locking of at least one degree of freedom between these two parts. The pedicle fixation 2 then abuts on the shoulder 121. As such, the intravertebral implant 1 has an additional support point in the pedicle. According to one embodiment, the vertebral implant 1 is not secured to the pedicle fixation 2 by screwing. According to one embodiment, the posterior part 12 of the intervertebral implant 1 assembled with the pedicle fixation 2 does not traverse either side of the pedicle fixation 2. According to one embodiment, the posterior part 12 of the vertebral implant 1 is mounted in the anterior inner portion 23 of the pedicle fixation 2.

As represented in FIGS. 7A and 7B, the expansion of the intravertebral implant 1 is performed by pulling on the central traction tube 13, by means of the tube 52 of the insertion instrument 5 (not shown in the figures). The central traction tube 13 can slide unidirectionally in the posterior part 12 of the implant 1 so as to enable deployment while preventing removal. Pulling the central traction tube 13 enables the deployment of the intervertebral implant 1 by moving the anterior and posterior ends of the anterior part 11 closer together. According to one embodiment, the deployment makes it possible to separate the plates in the vertebral body. This expansion in the vertebral body induces the anterior displacement of the implant: the anterior part 11 of the expandable implant slides through the anterior inner portion 23 so that the anterior part 11 of the intervertebral implant is adapted optimally to the environment wherein it is deployed. Advantageously, the sliding link between the posterior inner portion 23 of the pedicle fixation 2 and the posterior part 12 of the implant 1 is suitable for adapting the position of the intervertebral implant 1 deployed in the vertebral body independently of the position of the pedicle fixation 2.

As represented in FIG. 7B, the posterior part 12 can slide freely in an anterior inner portion 23, without however coming out thereof in order to provide permanent additional support, so as not to constrain the deployment of the intravertebral implant in a position dependent on the location of the pedicle fixation 2 in the pedicle. Indeed, the anterior inner portion 23 is configured to lock the translations and rotations of the intervertebral implant 1 along the x and y axes of the pedicle fixation 2, and enable the translation and rotation along the main axis of the pedicle fixation 2 (i.e. the z axis).

According to one embodiment, the dimensions of the posterior part 12 of the implant 1 are such that, once the posterior part 12 has been inserted into the anterior inner portion 23, the implant 1 can no longer be extracted from the pedicle fixation when it is implanted. The longitudinal dimension of the anterior inner portion 23 is sufficiently long so that the posterior part 12 remains inserted and partially secured to said anterior inner portion 23 during deployment. According to one embodiment, the length of the anterior inner portion 23 is indeed between 1 and 20 mm or between 5 and 15 mm.

According to this embodiment, the intravertebral implant 1 is free in axial rotation and in anterior translation with respect to the pedicle fixation 2. The deployment of the intravertebral implant 1 thus takes place only on the basis of the intravertebral bone environment which determines for the extendable anterior part 11 of the intervertebral implant 1 the orientation and depth of deployment of said extendable part. According to one embodiment, the intravertebral implant, and particularly the posterior part 12 thereof, can be moved along one, two, three, four, five degrees of freedom, preferentially two degrees of freedom, more preferentially one degree of freedom in rotation and one degree of freedom in translation, in the anterior inner portion 23. According to one embodiment, the intravertebral implant 1, and particularly the posterior part 12 thereof, can move in rotation and in translation along the z axis in the anterior inner portion 23.

According to one embodiment, after the expansion of the intravertebral implant 1, the rotation and translation along z between the intravertebral implant and the pedicle fixation are locked, thus securing the expandable intravertebral implant 1 to the pedicle fixation 2.

According to one embodiment, the anterior part of the intravertebral implant 11 is stabilised in the expansion position by injecting a filling material into the vertebra 4, via the at least one through hole 131. The filling material is injected by means of an injector through the pedicle fixation 2, the cylindrical recess 122 of the posterior part of the implant 12 and the hollow traction tube 13, up to the anterior part 11 of the implant 1.

According to one embodiment, the posterior part of the intravertebral implant 12 is secured to the pedicle fixation 2 by locking the relative movements of the posterior portion 12 with respect to the pedicle fixation 2 using securing means.

According to one embodiment, as illustrated in FIG. 8A, the posterior part of the intravertebral implant 12 is secured in the pedicle fixation 2 by injecting a filling material. The filling material is injected through the posterior inner portion 22 into the cylindrical recess 122 and into the at least one through hole 124 so as to come into contact with the inner surface of the anterior inner portion 23. Advantageously, the posterior portion 128 comprises a peripheral chamber 123 wherein the at least one through hole 124 opens. As such, the filling material fills the at least one through hole 124 and the peripheral chamber 123 in order to distribute the filling material at the interface between the posterior portion 128 and the anterior inner portion 23 and thus increase the contact surface area. In order to reinforce the securing further, the anterior inner portion 23 comprises at least one groove 231 and the filling material injected into the cylindrical recess 122 fills the at least one through hole 124, the peripheral chamber 123 and the at least one groove 231 of the anterior inner portion 23. Advantageously, the solidification of the filling material in the at least one axial groove 231 reinforces the securing according to the degree of freedom in rotation about the z axis. Advantageously, the solidification of the filling material in the at least one transverse groove 231 reinforces the securing according to the degree of freedom in translation along the z axis. Advantageously, the solidification of the filling material in the at least one oblique groove 231 reinforces the securing along the degrees of freedom in translation and rotation along the z axis. Advantageously, the solidification of the filling material in the at least one groove 231 of non-constant cross-section reinforces the securing according to the degree of freedom in translation and rotation along the z axis. According to one embodiment, the grooves 231 further enable the injection of the filling material to the anterior inner portion 23 reinforcing the securing further. According to one embodiment, the filling material injected into the cylindrical recess 122 fills the at least one through hole 124, the peripheral chamber 123 and the at least one groove 231 of the anterior inner portion 23, and all or part of the volume of the anterior inner portion 23. Advantageously, the peripheral chamber 123 makes it possible to reach the grooves 231 independently of the orientation of the intervertebral implant 1, and particularly of the orientation of the posterior portion 128, in the pedicle fixation 2.

According to one embodiment, as illustrated in FIG. 9A, the posterior part of the intravertebral implant 12 is secured in the pedicle fixation 2 by means of a conical expansion cap 6. Said conical cap comprises an external thread and a flared posterior end. Said cap 6 is inserted through the posterior inner portion 22, optionally after injecting cement into the vertebra via the through hole 131, and targeted in the internal thread 126 of the posterior portion 128. When the conical cap 6 is screwed into the internal thread 126 of the posterior portion 128, the flared end of the cap abuts against the flared end of the posterior portion 127 causing the radial deployment of the posterior portion, enabled by means of the slots 125. Advantageously, the radial deployment of the posterior portion 128 in the anterior inner portion 23 secures the posterior part of the intravertebral implant 12 in the pedicle fixation 2 by pressing.

According to one embodiment, once the intravertebral implant 1 has been deployed, secured to the pedicle fixation 2 and stabilised, if required by means of the injection of specially adapted bone cement or substitute, it is then possible to secure (i.e. connect) to the pedicle fixation 2—intravertebral implant 1 assembly the posterior element 3 by merely screwing and fastening same in the posterior inner portion 22 of the pedicle fixation 2. In this embodiment, the posterior element 3 is at least partially external to the vertebra 4 and is then capable of receiving posterior fixation elements such as rods or artificial ligament systems or any other means for stabilising the vertebral facture known to those skilled in the art.

The present invention also relates to a method for treating vertebral fractures comprising:

-   -   insertion of an implant system according to the invention         wherein the posterior part 12 is already inserted into the         anterior inner portion 23 in a vertebra 4 and screwing of the         pedicle fixation 2 in the vertebral pedicle by means of the         external thread 21;     -   expansion of the anterior part 11 of the intravertebral implant         1, particularly by pulling the central traction tube 13;     -   positioning of the anterior part 11 of the intravertebral         implant in the vertebral body enabled by the movement of the         posterior part 12 of the intravertebral implant 1 in translation         and rotation, along the main axis of the pedicle fixation 2, in         the anterior inner portion 23 of the pedicle fixation 2;     -   optionally, injection of a filling material into the vertebral         body via a through hole 131 to stabilise the anterior part of         the intravertebral implant 11; and     -   optionally, securing of the posterior part 12 in the anterior         inner portion 23. 

1. An expandable intravertebral implant system comprising an intravertebral implant comprising an expandable anterior part in a vertebral body and a posterior part; and a pedicle fixation comprising a posterior inner portion and an anterior inner portion defining a hollow portion for receiving the posterior part, wherein the posterior part of the intravertebral implant can move along at least one degree of freedom.
 2. The expandable intravertebral implant system according to claim 1, wherein the pedicle fixation comprises an external thread ensuring the anchoring of said pedicle fixation in a vertebral pedicle.
 3. The expandable intravertebral implant system according to claim 1, wherein the pedicle fixation comprises a main axis and the posterior part of the intravertebral implant can move in translation and in rotation, along the main axis of the pedicle fixation, in the anterior inner portion of the pedicle fixation; in such a way that the direction of expansion of the anterior part of the intravertebral implant is independent from the position of the pedicle fixation in the vertebral pedicle.
 4. The expandable intravertebral implant system according to claim 1, wherein the anterior part of the intravertebral implant comprises a first and a second plates, suitable for respectively forming a first and a second bearing surfaces in a vertebral body; these two surfaces being suitable for being separated from one another along a predefined expansion plane.
 5. The expandable intravertebral implant system according to claim 1, wherein the anterior inner portion comprises at least one groove on the inner surface thereof.
 6. The expandable intravertebral implant system according to claim 1, wherein a posterior portion of the posterior part of the intravertebral implant comprises a cylindrical recess and at least one securing means suitable for locking in rotation and in translation the relative movements between the intervertebral implant and the pedicle fixation.
 7. The expandable intravertebral implant system according to claim 1, wherein a posterior portion of the posterior part of the intravertebral implant comprises a cylindrical recess and at least one securing means suitable for locking in rotation and in translation the relative movements between the intervertebral implant and the pedicle fixation, and wherein the securing means comprises at least one through hole, passing through the posterior portion, and a peripheral chamber to the surface of the posterior portion in fluid communication with the at least one through hole.
 8. The expandable intravertebral implant system according to claim 1, wherein a posterior portion of the posterior part of the intravertebral implant comprises a cylindrical recess and at least one securing means suitable for locking in rotation and in translation the relative movements between the intervertebral implant and the pedicle fixation, and wherein the securing means comprises at least two slots extending axially along the posterior portion, an internal thread and a flared posterior end; suitable for engaging with a conical expansion cap.
 9. The expandable intravertebral implant system according to claim 1, further comprising a posterior element, partially external to the vertebra and secured to the pedicle fixation.
 10. The expandable intravertebral implant system according to claim 1, further comprising a posterior element, partially external to the vertebra and secured to the pedicle fixation, wherein the posterior element is secured to the pedicle fixation by means of a threaded rod screwed into an internal thread of the posterior inner portion.
 11. The expandable intravertebral implant system according to claim 1, further comprising a posterior element, partially external to the vertebra and secured to the pedicle fixation, wherein the posterior element comprises a posterior portion suitable for assembly with additional posterior fixation elements. 